Rats are omnivores, but many prefer meat when they can get it. House and brown rats usually use humans for their primary food source. They will scavenge through trash or eat any food that is left unprotected.
Rats have also been known to eat grain or kill insects, water creatures such as snails, fish and mussels, small birds, mammals and reptiles for food. Other rats, such as the Sulawesi white-tailed rat and Hoffman’s rat, prefer vegetarian fair such as seed and fruits, according to Encyclopedia Britannica.
By: Live Science